Transmission system



Nov. 3, 1925. I 1,559,850

W. L. CASPER TRANSMIS S ON SYS TEM Filed April 8. 1922 Patented Nov. 3, 1925.

UNITED STATES l 1,559,850v PATENT OFFICE.

WILLIAM L. CASPER, OF BROOKLYN, NEW YORK, ASSIGNOR'TO WESTERN ELECTRIC COMPANY, INCORPORATED, GN'EW YORK, N. Y., A CORPORATION OF NEW YORK.

TRANSMISSION SYSTEM.

Application led April 8, 1922. Serial No. 550,596.

To all whom t may concern.'

Be it known that I, WILLIAM L. CASPER, a citizen of the United States, residing at l I Brooklyn, in the county of Kings, State of New ork, have invented certain new and useful Improvements in Transmission Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to transmission sysemploying'electric discharge devices.

Anobject of this invention is to eliminate capacity effects between transformer windings included in a transmission circuit, wherein' hi gh quality transmission is desired.

Another vobject is to prevent. capacity effects in a translating device from distorting signal waves impressed therethrough p upon amplifying means such as electric discharge repeaters.

In accordance with the specific form of this invention hereinafter described in detail, the input 'transformer of an electric discharge repeater has its primary and secondary windings wound in such a manner and so associated with the input terminals of the repeater, that capacity effects existingl between the windings are eliminated. If the primary winding of the transformer is wound next to the core, with the secondary winding, superposed on the primary winding, the outer `layer of the primary winding is maintained at substantially ground potential, and the inner layer of the secondary winding is connected to that input terminal of the repeater, which is,usually groundedduring operation, and which terminal is usually the heated electrode or cathode. 'With this arrangement, the capacity e'ects betems and particularly to repeating systems tween the transformer windings are substan- 12 is employed for amplifying and repeating 55 signals in the reverse direction. The amplifiers may be of any desired type and three electrode vacuum tube repeaters are illustrated, comprising respectively,cathodes 13,

control electrodesl, 16, and anodes 17 60 In accordance with this invention, the input electrodes 13 and 15 of amplifier 11 are coupled with line section 7 by an input transformer 19, arranged in such a manner that y amplifier 11 is enabled to produce a faithful amplified cop;r of the signals received from line section without having the si 'al -1 waves distorted on account of capacity e ects between the transformer windings. The in- 70 put transformer 19 comprises a multi-layer primary winding 20. and amulti-layer secondary winding 21. The primary winding is shown to be in Itwo sections which may, for example, be wound on different parts of the core,in such a manner as to be aiding `for series currents, while the secondary winding is shown to be of only one section. In case the primary winding of the transformer iswound next to the core, and the secondary "00' winding is superposed on the primary wind-v ing, a connection 22 is provided to groundl for the' outer layers of the' two sections of the primary winding, while the secondary winding is so connected to repeater 11 that the 85 inner layer of the secondary winding is connected to that' electrode of the vacuum tube repeater, which in the operation of the device is maintained at substantially grounded potential. Since it is preferable to ground l the cathode, the inner layer of the secondary windin is shown to be connected to cathode 13 whi e the outer layer of the secondary wmding is connected to control electrode15 which is the other input terminal for the repeater. Thedotted capacities 24 and 2'5 represent the natural capacities whichexist between the adjacent layers of the 'primary and secondary windings of the transformer. Due to `ground connection 22 for that layer 100 of the primary winding adjacent to secondary winding and the ground connection 26 for thel cathode, it is evident that these natural capacities 24: and 25 have both terminals at substantially ground potential, so that these capacities are elimnated.- The presence of thesev capacit effects would cause the transformer coupling `te comprise'an in;-

pedance, a portion of which varies `with the frequency, thereby producing considerable distortion in the signals received from line 7 and impressed on the input of the amplier, a distortion effect which would be greatly amplified by amplifier 11. lVith the connecf `tion shown, however, theseJ capacity effects e 4mary winding is preferable, since a ground connection for any other point of the primary winding would tend to cause line section 7 to be unbalanced with respect to ground. It is also preferably that the secondary winding be wound in a single section so that all the turns of that layer of the secondary winding adjacent the primary winding, may be grounded by a path which does not include any turns of 'other layers to the secondary winding. While the ground connections 22 and 26 are shown to be fmade without the intermediary ofany impedance devices, such an arrangement is not essential as long as each of the paths 22 and 26 is of low impedance to the frequency of the alternating current signals to be transmitted. The grounding of the midpoint of the primary winding may be made in any suit-ab e manner such as through the intermediary of a grounded shield between the primary and, secondary windings.

It frequently will not be necessary to provide an actual path to ground for the mid point of the primary winding 20, since if the two wires of line 7 are at equi-potential with respect to ground, the mid-point of winding 2O will be at ground' potential independent of an actual connection to ground, such as shown at 22. In case the two wires of line 7 are unbalanced with respect to ground, one of the sections of the primary winding 20 should be of a greater number of-turns or layers than the other section, thereby compensatingfor the unbalance of line 7 and enabling those layers of' the primary winding adjacent the secondary to be substantially at the desired ground potential.

If the luid-point of the primary winding 2O is not actually grounded. the transformer construction of'this invention has an additional advantage in suppressing longitudinal currents in the repeater circuit. For example undesired longitudinal currents in leads 30 and 31 will fiow through the two halves of winding 20 in opposite directions and through capacities 24; and 25 to the ground connection 26 for the cathode. Duc

to the fact that these currents How/in opposite directions in the primary winding, the potentials induced in the secondary winding of the transformer will neutralize each other and will, therefore, produce no 1. A transformer having a multi-layer winding,

a second multi-layer winding .superimposed on the first mentioned winding, a direct low impedance connection to ground for the outer layer of said first mentioned Winding, and a direct connection of low impedance to ground for the inner layer of said second winding. Y

2. A transformer, having a multilaver winding, a second multi-layer winding` superimposed on the first mentioned winding, means for maintaining the mid-point of the outer layer of said first mentioned winding substantially at ground potential, and

means for maintaining the inner layer of said second winding substantially at ground potential.

3. In combination, a transformer having a primary winding anda secondary winding, an incoming line associated with said primary winding, an outgoing line associated with said secondary winding, and ounded connections for said primary win ing `and said secondary winding for shunting out the natural capacityV present between adjacent layers of said primary winding and said secondary winding. i

4. A transformer comprising a multilayer winding wound in a plurality of sections, a second winding wound in a single section, means for 'maintaining the mid-point of the irst mentioned windingat substantially ground potential, and means for main? taining substantially at ground potential one terminal of that layer of said second winding adjacent said first mentioned winding.

5. A transformer for signaling circuits comprising a multilayer primary winding. a multilayer secondary winding, means for maintaining at substantially ground potential that layer of said primary winding adjacent the secondary winding, and means for maintaining at substantially ground potential that laye'r of said secondary Winding adjacent the. primary winding.

6. A transformer for coupling a balanced two wire line to a second line having one slde grounded, said transformer'oomprising iso a multilayer primary winding connected to winding connected to the grounded side of the first mentioned line, a multilayer secsaid second line and havin a remote layer ondary Winding connected to said second connected to the ungroun ed side of said 10 line, and means for 'maintaining at substansecond line.

5 tially ground potential the mid-point of said In witness whereof, I hereunto subscribe primary Winding, said secondary Winding my name this 4th day of A ril A. D. 1922. having that layer adjacent said primary WILLIAM CASPR. 

